Elastomers for use in rotary regenerator assemblies are known, e.g., see U.S. Pat. No. 4,148,354 which is herein hereby incorporated herein by reference. These assemblies comprise ceramic core surrounded by a steel ring gear with elastomer therebetween. The elastomer accomodates differential rates of expansion during assembly and during operation.
Materials proposed in U.S. Pat. No. 4,148,354, while satisfactory, do have certain deficiencies. For example, the materials may not function optimally under certain conditions for as long periods as might be desired.
A particularly acute problem is that these materials tend to degrade during extended high temperature service. Others have proposed certain filled organosiloxane and other organic polymers for use in making articles that resist degradation when exposed to extreme conditions. See, for example, U.S. Pat. Nos. 3,098,836; 3,255,152; 3,274,145; 3,506,607; 3,676,420; 3,746,662; 3,791,998; 3,865,784; 3,867,315; 3,911,045; 4,025,485; and 4,069,083. These patents show that desirable properties may result by loading certain organic polymers with inorganic particulate.
It has been discovered in accordance with this invention that besides enhancing certain physical properties as well as potentially reducing material costs, certain particulates also offer improved thermal stability. Improved thermal stability is insufficient by itself, however, to provide a more acceptable material for applications such as ring gear assemblies. Rather, such improved thermal stability, when provided by increased particulate loading, is accompanied typically by higher initial viscosities and shorter working times. The higher initial viscosities and shorter working times can make such materials undesirable for high volume production use.
Others (see U.S. Pat. No. 3,499,859) have suggested use of particulates such as boron nitride to make thermally conductive RTV rubbers.
As distinguished from U.S. Pat. No. 3,499,859, this invention relates to two component systems that do not require an inert atmosphere during compounding. Moreover, the aging characteristics of elastomers of this invention make them of particular value, not seen in the U.S. Pat. No. 3,499,859 disclosure.
It is an object of this invention to provide elastomers with improved thermal stability.
It is also an object of this invention to provide elastomers with improved thermal stability and whose precursors have desirable initial viscosities and working times.
It is an additional object of this invention to provide elastomer precursors for filling difficult to fill mold cavities.
It is even a still further object of this invention to provide improved elastomer for use in rotary regenerators comprising ceramic core surrounded by steel or other metal ring gear.
These and other objects have been accomplished with elastomers made in accordance with the hereinafter disclosed invention.